Process of rendering undevelopable the silver halides present in an outer layer of multilayer color film



Eaten'ted Apr. 28, 1953 PROCESS OF RENDERING UNDEVELOPABLE THE SILVER HALIZDES PRESENT IN AN OUTER LAYER OF MULTILAER COLOR FILM Donald E. Sargent, Alton, 111., assignor to General Aniline & Film Corporation, New York, N. Y.,.

a corporation of Delaware No Drawing. Application May 5, 1950,

Serial No. 160,393

4 Claims.

The present invention pertains to the differential treatment of one or more but not all layers of a photographic multilayer film for the purpose of blocking or rendering undevelopable silver halides contained in such layer or layers.

There are many processes for treating photographic multilayer film in which it is necessary to differentially block the silver halides in one or more layers thereof. U. S. P. 2,424,256, for instance, discloses the formation of azo dye images in multilayer material by employing as the developer a B-aromatic sulfonhydrazide. It has been found that it is relatively easy to select color couplers which react with the oxidation products of the fi-aromatic sulfonhydrazides to yield yellow and magenta azo dyes. It is, however, a rather difficult problem to select a color coupler reactive with such oxidation products to yield a cyan azo dye. It is therefore the practice when utilizing the ,B-aromatic sulfonhydrazides as color developers to produce therewith yellow and magenta azo dyes in the blue and green sensitive layers respectively, but to use one of the conventional color developers, such as a p-dialkylaminoaniline, to produce a cyan azomethine dye image in the red sensitive layer.

It has been found that, when proceeding in this manner, the yellow and magenta azo dyes are developed satisfactorily with the sulfonhydrazide developer without developing the silver halide in the red sensitive bottom layer. However, when the second development with the pphenylene-diamine developer is run, a cyan was formed as expected in the bottom layer, but in addition, coupling occurs in the two upper layers between the azo couplers there present and the p-dialkylamino aniline developer. This reaction is undoubtedly attributable to the oxidation of the developer by residual incompletely developed silver halides in the two upper layers and the resulting coupling of the oxidation products.

The result of this action is a heavy undesired stain in the two upper layers which very seriously affects the color rendition of the material.

U. S. Patent 2,191,502 discloses a method for producing reversed images by the method known as the selective second exposure and color development method.

British Patent 501,040 indicates that in this procedure the latent images are not completely developed out in the various reversal development steps. As a consequence, in the second reversal development, incompletely reduced silver halides in the layer which is first developed in color is reduced. This means that color will be formed in plete reduction of residual silver halide before the next color development step.

There are many procedures extant dealing with the formation of masking images to improve the printing of negative color images. It has been found that the yellow imageas usually formed has satisfactory characteristics for printing. The same is not true, however, of the magenta and cyan images and it has been proposed to correct these images by forming red or yellow positive correction masks in the layers bearing such neg-" ative images. Inasmuch as the layer containing the yellow negative image is not masked, it is evident that differential processing is required in order to limit the masking to the green and red sensitive layers.

It will be apparent that in the above and similar procedures, the residual silver halides in certain of the layers of multilayer film must be either removed or blocked in order to facilitate the processing of the film. In other words, by rendering undevelopable the residual silver halides in certain of the layers in the tripacks in question, processing may proceed without the disadvantages oiten encountered in the Working up of such materials to the desired colored images.

I have now found that such residual silver halides 1n the tripacks'contemplated 1n the above and similar procedures can be effectively blocked being removed in the usual fixing baths. More important still is the fact that alkaline solutions of such compounds penetrate silver halide emulsions at a relatively slow rate. Because of this, the diffusion of the compounds into silver halide emulsion layers may be controlled to the extent desired to thereby permit selective processing of a particular layer or layers.

The diiferential treatment of multilayer material to block or render undevelopable silver halides in one or more than one but not all of the layers of a multilayer photographic color material constitutes the purposes and objects of the present invention.

As stated the compounds, the alkaline solutions of which are employed in my procedure, are 2- thiobarbituric acid, the 1-aryl-, 1-alkyl-, l-aralkyland 1-alkylene-derivatives thereof and thioureas substituted on one nitrogen atom by a hydroXy naphthyl group. Examples of such compounds are:

1-phenyl-2-thiobarbituric acid, l-(fl-naphthyl) -2-thiobarbituric acid, l-(fl-naphthyl) -2-thiobarbituric acid. 1-toluyl-Z-thiobarbituric acid, 1-methyl-2thiobarbituric acid, 1-ethyl-2-thiobarbituric acid, 1-propyl-2thiobarbituric acid, 1-butyl-2-thiobarbituric acid, 1-octyl-2-thiobarbituric acid, 1-decyl-2--thiobarbituric acid, 1-dodecyl-2-thiobarbituric acid, 1-benzyl-2-thiobarbituric acid, 1-(I-methyl-Z-naphthyl) -2-thiobarbituric acid, 1-allyl-2-thiobarbituric acid, 1-isopropeny1-2-thiobarbituric acid, -thioureido-l-naphthol, 8-thioureido-l-naphthol, Y-thicureido2-naphthol, G-thioureido-l-naphthol.

The above thioureido naphthols are included with the thiooarbituric acids for the reason that, like the thiobarbituric acids, the thioamide grouping therein has the known ability under salt forming conditions to isoinerize to the isothioamide grouping:

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| Lea All of the above compound exhibit solubility in aqueous a kaline solutions, i. e., of sodium carbonate, potassium carbonate, sodium hydroxide, and the like, and are conveniently applied from such solutions in the form of their water soluble alkali salts.

There are, of course, other agents which will render silver halide non-developable or render them less amenable to development. Such co 1.- pounds are, for example, potassium iodide (which operates to convert the silver chloride or bromide to silver iodide), sodium sulfide (whichoperates to convert the silver halide to silver sulfide) and the like. The compounds contemplated herein, however, have the distinct advantage over such compounds in penetrating the emulsions at a reasonably slow rate so that the depth of blocking may be controlled. Thus by controlling the concentration of the treating solution, the pH thereof, the temperature and the degree of agitation, the rate of penetration may b adjusted so as to cause a sharp line of demarcation at the depth desired. It is manifest that by controlling these factors, the time of treatment is likewise necessarily adjusted.

It is clear that the above factors will depend upon the thickness of the layers which are to be treated, the particular compositions thereof, and the like. Generally, however, the quantity of the compound in the treating solution will vary in amount of from 0.1 to 5.0 grams per 100 00., the quantity of alkali will be such as to give a pH between 8.0 and 11.5, and thetemperature I standard color developer will vary from 10 C. to about 25 C. Anyone skilled in the art by adjusting the various factors within these ranges will by simple experimentation be able to arrive at optimum control of the treating operation.

The invention is further illustrated by the following examples, but it is to be understood that the invention is not restricted thereto.

Example 1 A multilayer film strip, containing in the outer layer the non-diffusing pyrazolone referred to in Example '7 of U. S. P. 2,186,849, in the green sensitive layer the non-diffusing H-acid derivative ref-erred to in Example 5 of U. S. P. 2,424,256, and in the red sensitive layer, the reaction product of stearic acid with 8-amino-1-naphthol-4- sulfonic acid, was treated in the following manner:

(1) Exposed to white light,

(2) Bathed with agitation in a .5% solution of 2-thiobarbituric acid in 6.75% sodium carbonate solution for 1%; minutes at 18 C.,

(3) Washed 5 minutes in running water at 18 C.,

(4) Color developed 12 minutes at 18 C. in a solution containing p-diethylainino aniline,

(5) Washed 5 minutes in running water at 18 C.,

(6) Bleached in a ferricyanide bleach containing bromide until all developed silver was converted to silver bromide,

(7) Washed 5 minutes in running Water at 18 C.,

(8) Silver halide removed by fixing in 20% hypo solution,

(9) Washed 5 minutes and dried.

The strip so treated was a brilliant cyan color and microtome sections viewed under a microscope showed that the cyan was in the bottom layer only and that the upper layers were free from stain and dye.

Example 2 A film constructed as described in U. S. P. 2,191,502 was processed according to the method outlined in said patent (column 1, page 2), excepting that after the first and second reversal developments, the film was bathed with agitation in a .5% solution of l-(a-naphthyl)-2-thiobarbituric acid for about 1 minute at 18 C. By the interposition of this treatment, the transparency obtained showed no color distortion as the result of the action described in British Patent 501,040.

The procedure is the same as in Example 1, excepting that the 2-thiobarbituric acid is replaced by an equivalent amount of 5-thioureido-1-naphthol.

Various modi tions of the invention will occur to persons .ed in this art and. I therefore do not intend to be limited in the patent granted except as necessitated by the appended claims.

I claim:

1.. The process of selectively blocking or rendering undevelopable the developable silver halides present in an outer layer of a multilayer color photographic film having a plurality of adjacent developable silver halide layers which comprises treating such with an aqueous alkaline solution of a compound capable of rendeficg silver halides unreduceable by photographic developers and selected from the class consisting of Z-thiobarbituric acid and a thioureido naphthol while preventing the difiusion of such solution beyond the said outer layer in which the silver halides are to be rendered undevelopable and subjecting the so treated film to color development whereby a dye image is formed by such development only in such layer of said film to which said treating solution did not diffuse during said treating step.

2. The process as defined in claim 1 wherein the treatment is effected with an aqueous alkaline solution of 2-thiobarbituric acid.

3. The process as defined in claim 1, wherein the treatment is effected with an aqueous alkaline solution of 5-thioureido-1-naphthol.

4. The process of restricting color development to the lowermost layer of a multilayer color photographic material having at least three silver-halide emulsion layers in superposition, each layer of which is sensitive to a primary color and containing a color former fast to diffusion in the emulsion and capable of reacting with the oxidation products of primary aromatic amino developer to yield a dye image complementary in color to that for which the layer is sensitized, which comprises exposing said material to white light, bathing the same in an aqueous alkaline solution of a 2-thiobarbituric acid while preventing the diffusion of such solution to the innermost layer, and subjecting the so treated film to color development whereby a dye image is formed by such development only in the innermost layer of said material to which said treating solution did not diffuse during said treating step.

DONALD E. SARGENT.

References Gited in the file of this patent UNITED STATES PATENTS 

1. THE PROCESS OF SELECTIVELY BLOCKING OR RENDERING UNDEVELOPABLE THE DEVELOPABLE SILVER HALIDES PRESENT IN AN OUTER LAYER OF A MULTILAYER COLOR PHOTOGRAPHIC FILM HAVING A PLURALITY OF ADJACENT DEVELOPABLE SILVER HALIDE LAYERS WHICH COMPRISES TREATING SUCH FILM WITH AN AQUEOUS ALKALINE SOLUTION OF A COMPOUND CAPABLE OF RENDERING SILVER HALIDES UNREDUCEABLE BY PHOTOGRAPHIC DEVELOPERS AND SELECTED FROM THE CLASS CONSISTING OF 2-THIOBARBITURIC ACID AND A THIOUREIDO NAPTHOL WHILE PREVENTING THE DIFFUSION OF SUCH SOLUTION BEYOND THE SAID OUTER LAYER IN WHICH THE SILVER HALIDES ARE TO BE RENDERED UNDEVELOPABLE AND SUBJECTING THE SO TREATED FILM TO COLOR DEVELOPMENT WHEREBY A DYE IMAGE IS FORMED BY SUCH DEVELOPMENT ONLY IN SUCH LAYER OF SAID FILM TO WHICH SAID TREATING SOLUTION DID NOT DIFFUSE DURING SAID TREATING STEP. 